The Lepidoptera Galleria mellonella "in vivo" model: a preliminary pilot study on oral administration of Lactobacillus plantarum (now Lactiplantibacillus plantarum).

This work aims to assess the in vitro adhesion of two type strains of Lactobacillus plantarum (ATCC 14917 and ATCC BAA-793) (now Lactiplantibacillus plantarum). The experiments were conducted both in vitro on colon cells lines (Caco-2 and HT-29) and in vivo by adopting Galleria mellonella, a well-known alternative preclinical model. Data comparison obtained from in vitro and in vivo assays showed that adhesion performance is comparable in both models. Moreover, the type strain BAA-793, originally isolated from human saliva, showed enhanced adhesion performance, either in vitro to the low mucus-producing cell line (HT-29) or in vivo into the G mellonella gut. These results suggest a possible adaptation of this strain to its ecological niche compared to ATCC 14917. This preliminary pilot study, once again, showed the reliability of G. mellonella oral administration model as a first-line screening tool for in vitro to in vivo translation. Also, for the first time, the permanence of Lactobacillus strains into G. mellonella gut has been reported, reinforcing the claim that this preclinical model can be used, together with standardised in vitro and in vivo procedures already accepted across the scientific community, for the evaluation and investigation of new potential probiotic strains.